package day15;

import java.util.Scanner;

public class demo1 {
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        long x=in.nextInt();
        long a=(long) Math.pow(x,0.5);
        long ret=Math.abs(a*a-x)<Math.abs((a+1)*(a+1)-x)?a:a+1;
        System.out.println(ret*ret);
    }
}
